Means for angularly joining rigid metal tubing including a flat key element



MEANS FOR ANGU OINING RI ME TUBING y 1958 w. s. PEARSO 2,835,513

LARLY J INCLUDING A FLAT KEY MEN Filed Dec. l5, 19

F 4 [-711 TATFF' 10 51 572223? W1! [jam 5. Pearson MEANs FOR ANGULARLYJOINING RIGID METAL TUBING INCLUDING A FLAT KEY ELEMENT William S.Pearson, Baltimore, Md. Application December 13, 1954, Serial No.474,699

2 Claims. (Cl. 285-222) The present invention relates to a new andimproved means for angularly joining rigid, hollowmetal tubing memberswherein an end portion of one of the hollow tubes is deformed into tightlocking engagement within the interior of another hollow tube.

In accordance with the general features of the instant invention, meansare provided whereby the end portion of a first rigid hollow metal tubeis disposed angularly within the axial bore of a second tube and thetubes locked together by expansively deforming the end portion of thefirst tube into tight locking engagement with the interior of thesecond.

A principal feature of this invention lies in the provision of means forexpansively deforming the end portion of a-tube disposed angularlywithin the axial bore of another, such means comprising a novel keycarried by the end portion of the former tube and which responds to andreacts to axial pressure applied to the tube upon which the key iscarried by expansively deforming the end portion of the tube into tightlocking engagement with the interior of another tube.

It is, therefore, an object of this invention to provide a means forangularly joining rigid, hollow metal tubes.

Another object is the provision of a novel key which allows the endportion of one rigid, hollow metal tube to be expansively defonned intotight locking engagement with the interior of another tube.

A further object is the provision of a hollow, rigid metal tubingconstruction in which one tube is held in locked angular engagement withanother tube by expansively deforming an end portion of the former intotight locking engagement with the interior of the latter.

Other objects, features and advantages of the present invention will bereadily apparent from the following detailed description of a preferredembodiment thereof taken in conjunction with the accompanying sheet ofdrawings, in which:

Figure 1 is a fragmentary elevational view of a pair of hollow, rigidmetal tubes angularly joined in accordance with the instant invention; 7

Figure 2 is a perspective view of one embodiment of the novel tubeexpanding key employed in the instant invention;

Figure 3 is a fragmentary, longitudinal sectional view with parts inelevation and parts in section illustrating the manner in which the keyshown in Figure 2 is employed in joining tubes together;

Figure 4 is a fragmentary sectional view with parts in section and partsin elevation taken through the union of two metal tubes joined inaccordance with the instant invention;

Figure 5 is a view taken substantially along the section line VV ofFigure 4; and

Figure. 6 is a perspective view of another embodiment of a novel tubeexpanding key which may be employed in the instant invention.

By way of illustration, the instant invention is illustrated in thedrawings in conjunction with the joining or union of two, hollow, rigid,metal tubes 10 and 11, respectively.

The tube 10, which is illustrated as having a substantially largerdiameter than the tube 11, has an axial bore 12 defined by a cylindricalwall 13. The smaller diametered tube 11, likewise, has an axial bore 14defined by a cylindrical wall 15.

Tube expanding and deforming means are provided 'for tightly locking theend portion of the tube 11 within the interior of the tube 10. Suchmeans (Figure 2) include a generally paddle-shaped tube expanding key 16adapted to be carried within the axial bore 14 of the tube 11 in an endportion thereof. To this end, the key 16 has a generally rectangularfirst part 17 which is dimensioned for snug slidable engagement withinthe bore 14, and a generallyrectangular, integral, larger second portion18 merging with the first part 17 in tapered relation thereto atshoulders 19 on the sides of the key. The corners of the smaller firstpart 17 and the larger second part 18, are rounded or chamfered. Thisaids in introducing the first part 17 into the axial bore of the tube 11and the second larger part 18 intoa suitable aperture formed in the wallof the tube 10.

The smaller, first part 17 of the key 16 is preferablytransverselydimensioned to have a width substantially equal to or justslightly smaller than the diameter of the axial bore 14 of the tube 11.To aid in retaining the key 16 inthe end portion of the tube 11 duringjoining thereof with the tube 10, the width of the first part 17 ispreferably such that the first part is slidably receivable snugly withinthe axial bore 14 of the tube 11.

The width of the larger sectiond portion 18 is greater than the width ofthe first part 17, and preferably is transversely dimensioned to have awidth substantially the equivalent of the outer diameter of the tube 11.

The length of the second part 18 of the key 16 may be substantiallyequal to or slightly smaller than the diameter of the axial bore 12 inthe tube 10. Preferably, however, the second part 18 is longitudinallydimensioned to have a length substantially equal to the diameter of theaxial bore 12 minus the thickness of the wall 15 of the tube 11. Thisinsures a tight fit between the outer periphery of the tube 11 and themargin of an aperture 20 provided in the wall of the tube 10 in whichthe tube 11 is inserted when the end portion thereof is expanded intotight engagement With the interior of the tube 10.

The key 16 may be formed from a suitable strip or sheet metal stock,such as by die punching or the like, and preferably having a sufiicienthardness and resistance'to bending and compressive deformation to allowexpansive tube wall deformation or displacement thereabout without beingdeformed itself.

In joining the tubes 10 and 11 together in a tight angular relationship,the aperture 20 is first formed in the cylindrical wall 13 of the tube10 (Figure 3). The aperture 20 preferably has a diameter substantiallyequal to the outer diameter of the tube 11 so that the tube 11 may beinserted therein and have a snug sliding fit with that part of the Wall13 defining the margin of the aperture 20.

The key 16 is disposed to be carried by the end portion of the tube 11by slidingly introducing the first, smaller width part 17 of the key 16into the axial bore 14 of the tube 11. When thus positioned, the key 16rests on the marginal extremity of the tube 11 on the tapered shoulders19 with the larger width second part 18 of the key projecting axiallybeyond the extremity of the tube 11.

on or butted against the inner surface of the wall 13 in axially to thetube 11 radially inwardly toward the tube 10 while solidly backing thewall of the latter exteriorly opposite the end of the key 16. As theassembly pressure is applied the second part 18 of the key 16 incooperation with the tapered shoulders 19 functions in a wedge-likemanner, allowing the inwardly moving tube wall 15 to be expansivelydisplaced or deformed over and'about the side edges of the second part18. To this end, the shoulders 19 provide means for guiding theexpansive deforming displacing movement of the end portion 11a of thetube wall over and about the, larger key part 18. As a resultdiametrically opposed locking means in the form of ribs 21 (Figs. 4 andare formed on the end portion 1111 within the tube 10. These ribs 21expand the inserted tube portion 11a to an over-all larger dimensionthan the aperture 20 and thus prevent withdrawal of the tube 11 from theassembled relation. In the region of the tapered shoulders 19 there isprovided by the outer ends of the ribs 21 a tight gripping, interlockingengagement with the marginal portion of the aperture 20 to effectivelyprevent rotation of the tube 11. Rotation is further prevented by thefact that as ribs are deformed or displaced outwardly as seen from theside in Figure 4, other parts of the end portion are deformed ordisplaced inwardly as shown from the top at 22 in Figure 5. Thisdeformation produces an outof-round configuration at the end of tube 11which coacts with the inner bore 12 of tube to lockingly preventrelative rotation of the tubes.

Additional locking of the tube 11 against rotation relative to the tube10 attains as a result of drawing in of the extremity of the tubeterminal portion 11a, as seen at 22 in Figure 5, toward the extremity ofthe key part 18, thus generally flattening the tube terminal parallel tothe axis of the tube 10. Interengagement of the tips of the flattenedsides 22 with the cylindrical bore 12 cooperates with the shoulderinterlock to resist relative turning as well as relative canting.

In Figure 6 is shown another embodiment of a tube displacing key whichmay be employed in the instant.

method. As seen therein this key 23 includes a first part 24 adapted tobe received within the axial bore of the tube 11 in the same fashion asthe first part 17 of the key 16. The key 23 also includes a secondintegral portion 25 adapted to project axially from the end portion of atube in which the key 23 is carried The second portion 25 merges withthe first part 24 at a pair of laterally opposite lug portions 26 formedon the side of the key 23.

The width of the key 23 in the region of the lugs 26 is preferablysubstantially equal to the outer diameter of the tube 11; the lugs 26acting in substantially the same wedge-like manner in guiding andeffecting tube displace ment as the shoulders 19 on the key 16.

The key 23 may be cut from suitable strip metal stock and the lugs 26formed thereon by upsetting the edge portions of the key by suitablepunch or die means.

It will be appreciated that the instant invention provides aneconomical, efiicient method whereby a pair of hollow substantiallyrigid metal tubes can be joined angularly in an improved manner. Noexternal fastening means are exposed to the exterior of the tube unionand, accordingly, the aesthetic qualities of the instant tube joint aresuperior to those obtainable by the use of rivets, brazing, welding orthe like.

In addition, by expansively deforming the end portion of one tube intotight locking engagement with the interior portion of another, largetube areas are contacted in locking relation making for a tighter andstronger union than is possible with rivets or similar externalfastening devices. Further it is not necessary to provide slots or holesthrough the tubes, such as is required in employing rivets or the like.This absence of apertures other than the aperture 20 formed in the tube10 to receive the tube 11, minimizes the possibility of ingress of waterwithin the tube construction and provides a more weather resistantjoint.

Although the instant invention is applicable for angularly joiningsubstantially all forms of rigid metal tubing, it is especially suitablefor producing ladders, play ground equipment, fences and scaffolds,besides many other uses.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention.

I claim as my invention:

1. In a rigid hollow tubing construction including a first tube havingan aperture formed in the wall thereof for receiving a second tube theimprovement comprising, a key including a first part adapted to becarried by the axial bore of the second tube in an end portion thereof,and an integral larger substantially flat second part, said second parthaving a length slightly less than the inside diameter of the secondtube, and an end remote from said first part defining a line transverseto the axis of said tube end portion, said second part adapted toproject axially therefrom for joint disposition with said end portionvia said aperture within the axial bore in the first tube with the endof said second part engaging the interior of said second tube along anaxial line, said key parts being smoothly joined by a shoulder portionproviding a camming surface adapted to react therein to axial pressureapplied relative to said end portion radially inwardly toward the firsttube to eifect and guide an out-of-round expansive tube deformation ofsaid end portion by said surface as said second tube is forced over saidsurface during movement of the said second tube past said surface tolock the tubes tightly against disengagement and relative rotation.

2. In a rigid hollow tubing construction, the combination of: a firsttube having an aperture in the wall thereof; a second tube having anout-of-round end portion extending inwardly of said aperture; and a keyincluding a first part thereof carried by the axial bore of said secondtube adjacent to said out-of-round end portion, and an integralsubstantially flat second part disposed within said end portion; saidsecond part having a length slightly less than the inside diameter ofsaid first tube and a width slightly less than the diameter of saidaperture, and an end remote from said first part engaging the interiorof said first tube along an axial line, said key parts being smoothlyjoined by a shoulder portion disposed slightly inward of said aperture;said out-of-round end portion having a transverse dimension slightlygreater than said aperture and snugly disposed intermediate saidshoulder portion and said aperture, whereby said tubes are positivelylocked against disengagement and relative rotation.

References Cited in the file of this patent UNITED STATES PATENTS1,010,427 Holden Dec. 5, 1911 1,521,805 Ellis Jan. 6, 1925 1,989,955 VanPatten Feb. 5, 1935 2,140,919 Mushet Dec. 20, 1938 2,415,232 Brock Feb.4, 1947 2,614,827 Peach Oct. 21, 1952 FOREIGN PATENTS 826,246 GermanyNov. 22, 1951 133 Great Britain Jan. 19, 1954

